DC energy storage system

Abstract

A DC energy storage system may include first and second DC terminals for connection to a DC link, a DC energy storage converter including a number of modules connected in series between the first and second DC terminals, each module including at least one switching element and at least one battery, the or each switching element and the or each battery in each module being combinable to selectively provide a voltage source, and at least one fire-resistant protective barrier arranged to separate the modules into converter sections, each converter section including at least one module of the number of modules.

I claim: 
     
       1. A DC energy storage system, comprising:
 first and second DC terminals for connection to a DC link; 
 a DC energy storage converter including a plurality of modules connected in series between the first and second DC terminals, each module including at least one switching element and at least one battery, the or each switching element and the or each battery in each module being combinable to selectively provide a voltage source; 
 at least one fire-resistant protective barrier arranged to separate the plurality of modules into converter sections, each converter section including at least one module of the plurality of modules; and 
 a fire detector configured to detect a presence of a fire in the converter sections, wherein a controller is programmed to, responsive to detection of the presence of the fire in one or more of the converter sections by the fire detector, determine whether the number of healthy modules in the DC energy storage converter is sufficient or insufficient to continue operation of the DC energy storage system if one or more faulty modules is removed from operation. 
 
     
     
       2. A DC energy storage system according to  claim 1 , wherein each converter section comprises multiple modules of the plurality of modules. 
     
     
       3. A DC energy storage system according to  claim 1 , wherein the controller is programmed to selectively control the switching of the switching elements of the modules so as to regulate a charge level of each battery. 
     
     
       4. A DC energy storage system according to  claim 1 , wherein each converter section comprises a bypass element connected across the corresponding module or modules, each bypass element operable to selectively divert a current flowing through the corresponding converter section to bypass the corresponding module or modules. 
     
     
       5. A DC energy storage system according to  claim 1 , wherein the plurality of modules are arranged in pre-assembled module devices, each pre-assembled module device comprising multiple modules of the plurality of modules and a local control unit programmed to control the switching of the switching elements of the modules in the same pre-assembled module device. 
     
     
       6. A DC energy storage system according to  claim 5 , wherein each preassembled module device comprises at least one local power supply device configured to supply power to the local control unit in the same pre-assembled module device, and the or each local power supply device is configured to source power from two or more of the batteries of the modules in the same pre-assembled module device. 
     
     
       7. A DC energy storage system according to  claim 1 , wherein each module comprises a capacitor or includes a capacitor-inductor filter. 
     
     
       8. A DC energy storage system according to  claim 1 , wherein each module comprises an isolation device that is activatable to electrically isolate the or each corresponding battery from the or each switching element of the same module. 
     
     
       9. A DC energy storage system according to  claim 8 , wherein the isolation device comprises at least one of a fuse and a disconnector. 
     
     
       10. A DC energy storage system according to  claim 1 , wherein the or each fire-resistant protective barrier is explosion-resistant. 
     
     
       11. A DC energy storage system according to  claim 4 , wherein the controller is programmed to, responsive to a determination that the number of healthy modules in the DC energy storage converter is sufficient to continue operation of the DC energy storage system if one or more faulty modules is removed from operation, operate one or more of the bypass elements to divert a current flowing through the DC energy storage converter to bypass the or each faulty module. 
     
     
       12. A DC energy storage system according to  claim 11 , wherein the controller is programmed to, responsive to a determination that the number of healthy modules in the DC energy storage converter is sufficient to continue operation of the DC energy storage system if one or more faulty modules is removed from operation, increase a voltage output of the healthy modules to compensate for removal of the or each bypassed faulty module from operation. 
     
     
       13. A DC energy storage system according to  claim 1 , wherein the controller is programmed to, responsive to a determination that the number of healthy modules in the DC energy storage converter is insufficient to continue operation of the DC energy storage system if one or more faulty modules is removed from operation, provide a control signal to shut down an electrical system of which the DC link forms part or to electrically isolate the DC energy storage converter from the DC link. 
     
     
       14. An electrical assembly, comprising: a DC energy storage system according to  claim 1 ; and a DC link, wherein the first and second DC terminals of the DC energy storage system is connected to the DC link.